Multistage compressor



Sept. 5! 1939. H, C 'GUlLD Re. 21,196 l MULTISTAGE COMPRESSOR I Original Filed Nov. 5, 1927 0 #sans ATTORNEY.

Reiaue'd sept. s, 1939 j Re. 21,196

PATENT ori-"ICE MULTISTAGE COBIPBSSOR Herbert C. Guild, New York, N. Y., assignon by mesne assignments, to General Motors Corpo- "ration, Detroit, Mich., a corporation of Deia- Original No. 1,748,394, dated February 11, 1930,`

Serial No. 231,179, November 5. 1927.

Application ior vreissue April 29, 1937,*Serial No.

This invention relates to gas, air or vapor compressors andmore particularly to those compressors used in retrigerating machines of what is known as the compression type.

One of the objects of the invention is to produce an apparatus of a more constant volumetric efficiency designed for handling of the gases compressed in such manner that their volume increase, due to superheating upon entering the apparatus, is held to a minimum.

Another object is to have the gases pass through the machine in a ilow or stage direction corresponding with the direction of heat of compression; the coldest gas entering at the coldest part of the apparatus, the intermediate temperature gas being confined to the intermediate temperatured part of the apparatus, and the hottest gas passing out at the hottest part of the apparatus, and by this means minimizing the heat or energy slip back from compressed high temperature gas to uncompressed low temperature gas.

Another object is to reduce the cost of a two stage compressor by utilizing the crank case or chamber for the inter-cooler space between stages.

Another object is to produce a higher pressure on the stufling box than the pressure in the low pressure side and a lower pressure on the stufiing box than on the high pressure side. f

Another object is to have the crank case oil chamber at a more eilicient oil separating temperature for the purpose of more easily evaporating any entralned refrigerating media that may pass into it.

Another object is to eliminate an open passage from the crank case to evaporator and thus prevent heat slipping back during the stop period into the low temperature side that has been already taken out.

Another object is to make a more compact and cheaper construction.

With the above mentioned and other objects in view, the invention. consists in the novel construction and combination ofparts hereinafter described, illustrated in the accompanying. drawing and pointed out in the claims hereto appended; it being understood that various changes in the form, proportion, size and minor details of construction within the scope of the claims may be resorted to without departing from the spirit or sacricing any of the advantages of the in- .vention.

To more fully comprehend the invention reference is directed to the accompanying drawing,

wherein 11 Claims. (Cl. 23u-191) Fig. 1 is a view in vertical section of one embodiment of the apparatus for carrying out my invention.

Fig. 2 is a similar view taken' on section line 2-2 of Fig. l. f

Inthe drawing wherein like characters of reference designate corresponding parts in the several views, I indicates a crank case provided in4 its side wall with an opening l2 closed by a removable plate 3. The plate 3 is provided with a shaft opening 'through which into the crank case extends a crank shaft s, the inner end of which rotates ina fixed bearing 5 on the inner face of `the opposite side wall. 6 ofthe crank case. A stuffing box l surrounds the shaft where it passes through the opening in the plate 3, vand the adjustable take-up l precludes pressure in the 'crank case passing 'therefrom around the shaft.

v'valves il and i8, illustrated in the form of plates,

the valve Il closing the port I5 of the piston il on the underside of the piston head, and valve i8 closing port i6 of piston i2 on the upper side of the piston head. l

It will thus be observed that the valves ofthe respective pistons operate in different directions. The cylinder 9 at a point slightly above the point of the lower end of 'the stroke of the piston thereilce 2l, controlled by an outwardly opening valve 2i, the oriiice connecting with a, pressure line' or container, not shown.

A drive or ily wheel 22 is' mounted on the end of shaft 4 and in the present embodiment power for rotating the shaft is delivered thereto.

The mechanism of the compressor is preferably splash lubricated, the lubricant being bcontained in the crank case and preferably main- `tained at the level indicated in the drawing, the

lubricant being supplied to the crank case through the filler opening, normally closed by a plug 23.

With the shaft l rotating in the desired direction, the down stroke of piston il will create a yvacuum in the cylinder I until the head of the in is formed with an inlet port I9, and the upper end of cylinder i0 is provided with an outlet ori-l 40 piston uncovers port Il. During this operation,y the downward movement of the piston, it being of greater displacement area than the lpiston in the adjoining cylinder, compremes the gases within the crank case. At this same time the piston I2 is moving upwardly in the cylinder Ill, and 'the gases contained within the cylinder above the pistonare compressed therein, seating valve I8, and on its pressure arriving at a point approximating that in the container, not shown, connected with the outlet orifice 2l, the valve 2| will be lifted and the gases discharged through the orifice 20. On the next cycle of operation, that is the upward reciprocation of the piston II will compress the gasesin cylinder 9 above the inlet orifice I9 and its pressure will unseat valve II, enabling the gas to pass downwardly into 'crankcase are precluded from escaping therethe crankycase. At this time piston I2 is moving downwardly, valve 2| being heldin closed positionv by the pressure in the container, not shown, and valvev I8 is,

unseated, admitting the passage of gases through ports I6, the gases passing through the ports being under pressure, due to the increased displace.

ment area ofpiston Il over that of piston- I2.

It will thus be observed that the gases entering the compressor through inlet I! are com.,-

pressed. in successive stages prior to passing through the orices 2li, also that the gases pass through the apparatus in a compression stage direction corresponding with the direction oi. heat of compression, the coldest gases being admitted into the cylinder 9; the intermediate'temperature gasesbeing contained in the crank case I, and the gases of highest temperature passing from the apparatus through the cylinder Il).

It will be observed that the valves in the present apparatus are of simple structure and `positive operation; also that the liability of the gases of. intermediate pressure -contained within the from around the shai't I by the stuiiing box 1.

Itwill be observed that the-rotation of the member 22 inr the form. of a ian wheel, directs a current of air over means or: elements 24, illustrated in the form of fins, associated with the crank case. LThis action removessome of the heat of compression produced in the first stage of compression, and also, should thev crank case receive entrained refrigerating media, raises the temperature ofv this media by directing air against the members 2|.

It will be observed that dependent on the tem.- perature within the crank case, the action of the air created by member 22 raises the temperature when one condition exists, and lowers the temperature to thatoi the surrounding air when another condition exists. l

While the means 24 is illustrated in the form of iins, it is to be understood that any suitable construction for accomplishingthe above result may be employed. When used in certain installations, it may be desirable to admit into the. crank case a gas of a pressure intermediate that in the cylinders 9 and III. -To accomplish this there is provided an inlet pipe 2E leading into the crank case and provided with a check valve 28 opening or unseating against the pressure in the crank case. This pipe 25l is preferably connected with or leads from an evaporator, not shown, and a valve 21 therein serves to interrupt the gas ilow therethrough. It will thus be apparent Vthat when a supply of gas is available at a pressure higher than that compressed in the cylinder Q and it is desired to amos compress this gas to a higher pressure in cylinder III, the same may be, without stepping it down and without efficiency loss delivered to the crank case I through'pipe 25 and raised to a higher compression in cylinder I0.

I claim:

1. ,A multiple-stage compressor comprising a crank case, a pair of cylinders opening therelnto and one of a greater area than the other,a piston in each cylinder, one of al greater dispiacement 'than the other, a port in each piston, a valve controlling the port in each piston, the

valve controlling the port in the piston of greatest displacement opening into the crank case, said crankcase having an effective volume greater than the displacement of saidvpiston, the valve controlling the port in the other piston opening into its cylinder, a valve controlled port leading from the latter cylinder, and a gas inlet port communicating with the cylinder of greatestV diameter.V

2. A multiple-stage compressor comprising a pair of compression elements. one of greater displacement than the other, a chamber intermediate the elements for receiving the compression from one element and transferring it to the other and `within which it is compressed by the action of said compression elements, a controlled inlet port into the element of greater displacement, a valvecontrolled outlet leading from the element of smaller displacement, and means for simultaneously operating said compression elements in opposite directions, said chamber constituting the crank case for said elements.

3. A multiple-stage compressor comprising a l plurality of compression elements, certain of the elements being of greater displacement than the ment andwithin which chamber the compressionl is held by the action of said compression elements, a controlled inlet port leading into the element of ,greater displacement, a valve controlled outlet port leading from another of the compression elements, means for simultaneously operating said compression elements, and means for admitting gas directly into the intermediate compression chamber at a pressure between that generated by the compression elements, said intermediate compression chamber constituting the crank case'for trolled outlet port leading from another o! thev compression elements, means for simultaneously operating said compression elements, means associated'with the chamber' for absorbing the heat or the gases within the chamber, and means for directing an air current onto the walls ot said means to maintain the temperature thereof substantially corresponding with atmospheric temperature, said chamber constituting the, crankcase of at least one oi.' said compression elements'. A multiple-stage compressor ,comprising aguj 

